The world's oldest earthquake-proof tomb

The tomb of Cyrus the Great, built more than 2,500 years ago, is considered the oldest structure with effective earthquake resistance.

In ancient Greece and Persia, a construction technique was developed in which other materials such as ceramic and clay were inserted between the ground and the foundation so that when the ground shook, one layer slid under the other, minimizing the damage caused by an earthquake, according to Amusing Planet. This technique, known as base insulation , is one of the most effective measures to protect buildings from earthquakes today . The earliest example of base insulation is the tomb of Cyrus in Pasargadae , the capital of the Achaemenid Empire under Cyrus the Great (559–530 BC) in Iran.

The tomb of Cyrus the Great. (Photo: Borna_Mirahmadian).

Although Cyrus the Great ruled over a vast empire that stretched from the Mediterranean Sea to the Indus River, his tomb was simple and modest. The tomb was roughly cubic in shape, measuring 6 x 5 m. A small door led down to a pit. The roof of the tomb was triangular. The chamber was located above a pyramidal base with six large steps. The tomb was built from large stones.

The tomb's foundation is made of several layers of limestone. The first layer is made of stones held together with mortar, a mixture of lime and ash or sand, and then polished. The upper layer is made of stones connected by metal rods but not connected to the layer below. This allows the upper layer to slide over the top of the lower layer in the event of an earthquake.

Cyrus's tomb has been hit by several earthquakes over the past 2,500 years, though researchers don't know how strong they were or whether they were strong enough to disrupt the "base isolation" structure. They found no signs of shifting rocks or layers. So far, they haven't been able to determine for sure whether the pyramid structure is a true "base isolation" design that protects the tomb.

According to the Greek historian Arrian of Nicomedia, who served as a general to Alexander the Great, the Macedonian king visited the tomb after sacking Persepolis. Alexander commanded one of his soldiers, Aristobulus, to enter the tomb. Inside, he found a golden bed, a table with drinking vessels, a golden coffin, and several jeweled ornaments.

A detailed study by the Islamic Azad University in Iran claims that the seismic isolation system at the base of the tomb of Cyrus the Great does exist. They simulated the tomb using software and subjected it to a strong earthquake before drawing their conclusions.